The trip of a lifetime: hallucinogen persisting perceptual disorder

The differential diagnosis of psychotic symptoms is broad and extends beyond primary psychotic and affective disorders. We aim to illustrate that the chronology and phenomenological nature of hallucinatory symptoms may provide clues towards alternative diagnoses, such as hallucinogen persisting perceptual disorder (HPPD). We describe the resurgence of visual pseudo-hallucinations in a young woman in the context of previous substance-induced hallucinatory symptoms and a prior diagnosis of occipital lobe epilepsy. She presented a diagnostic challenge, saw several emergency and specialist doctors and attracted stigmatising diagnoses leading to anxiety and depressive symptoms. Her symptoms were finally recognised as HPPD, and she was treated appropriately with lamotrigine.

Patients with perceptual disturbance can present in various clinical settings, and HPPD is an under-recognised diagnostic possibility. Delayed or misdiagnosis prolongs profound functional impairment and social decline, and predisposes the patient to the development of anxiety and depression and related increased risk of suicide.